Musk attorney Marc Toberoff said he submitted the bid to OpenAI's board of directors, according to the Journal.

"No thank you, but we will buy twitter for $9.74 billion if you want," OpenAI chief Sam Altman wrote in a post on X, formerly Twitter, apparently responding to the offer.

Musk, who bought X under its former moniker for $44 billion in 2022, replied to the post by simply writing: "Swindler."

Musk's attorney did not immediately respond to a request for comment.

The Tesla boss and close ally of US President Donald Trump has been mired in an ongoing feud with Altman, with Musk filing repeated lawsuits against the San Francisco-based OpenAI.

Musk co-founded OpenAI in 2015, with the company becoming the world's leading AI startup since he left in 2018. He launched his own generative AI startup, xAI, in 2023.

"We created a bespoke structure: a for-profit, controlled by the non-profit, with a capped profit share for investors and employees," OpenAI said in a December blog post that outlined a plan to become a Delaware Public Benefit Corporation.

The shift would require the company to balance the interests of shareholders, stakeholders, and the public in a tilt away from non-profit, according to the post.

Musk established xAI in early 2023 to have a foothold in the technology expected to disrupt how people live and work.

OpenAI is one of the world's highest valued startups, but loses money on the high costs of turning out its expensive technology.

Trump in January announced a major investment to build infrastructure for AI led by Japanese giant Softbank, cloud giant Oracle and OpenAI.

The venture, called Stargate, "will invest $500 billion, at least, in AI infrastructure in the United States," Trump said in remarks at the White House.

OpenAI co-founder and boss Altman, SoftBank's chief Masayoshi Son and Oracle founder Larry Ellison attended the announcement.

But Musk was quick to cast doubt on the project, saying the money promised for the investment actually was not there.

The comments marked a rare instance of a split between the world's richest man and Trump, with Musk playing a key role in the new US administration after spending $270 million on the Republican's election campaign.